Typical power cables, including those for small appliances to outdoor station-to-station power cables, often comprise one or more conductors in a core that may be surrounded by one or more layers. These layers may include one or more of the following: a first polymeric semi-conducting shield layer; a polymeric insulating layer; a second polymeric semi-conducting shield layer; and optionally, a metallic tape shield; and a polymeric jacket.
Semiconductive compositions may include resin components which are known to exhibit high dielectric losses when used in insulating compositions. While this may not be a problem in a semiconductive composition, species migration from the semiconductive layer into an adjacent insulation layer can lead to increased dielectric losses of the layered composite. Reduction in the migration of the diffusing species from the semiconductive layer into the insulation, or enhanced solubilization of this species within the semiconductive layer is expected to yield improved dielectric properties of the layered composite. This would be useful in electrical applications such as power cables.
Some elastomeric components used in semiconductive shield formulations may contain species that diffuse into the insulation, which leads to enhanced dielectric losses in power cables (especially at temperatures above the 90° C. normal operating temperature rating of the cable).
The present invention provides a means to enable the use of a class of elastomeric materials in the semiconductive compositions of the cable design that would otherwise lead to much higher cable dielectric losses in shorter aging times.